BOSTON — Republican presidential candidates jousted over conservative purity Sunday as they raced across the South, the Midwest and New England in a late scramble before the Super Tuesday contests that could settle the party nomination.
With polls suggesting that Republican voters were consolidating behind John McCain, the Arizona senator made a foray into former Gov. Mitt Romney's home state of Massachusetts. He greeted New England Patriots fans in a Boston tavern just before the team's Super Bowl kickoff and spoke openly of his plans for the general election.
Campaigning in Illinois and Missouri, Romney fought to keep McCain from establishing a sense of inevitability. He urged Republicans to pick a nominee with stronger conservative credentials, describing McCain as "indistinguishable from Hillary Clinton and Barack Obama" on immigration, the environment and taxes.
Romney also withstood a withering new assault from former Arkansas Gov. Mike Huckabee, who called on him to drop out of the race. Huckabee ridiculed Romney as a recent convert to conservative ideals, saying he had rankled many by "shouting 'Hallelujah' louder than the rest of us who have been in church a long time."
The religious imagery underscored the struggle for evangelical support between Huckabee, a former Southern Baptist minister, and Romney, who has encountered some voter prejudice against his Mormon faith. Evangelical voters will be a powerful force in Alabama, Oklahoma and other states.
For all of the major candidates, the party's 21 nominating contests from coast to coast on Tuesday pose a daunting challenge. With time running short, each traveled Sunday to targeted states and congressional districts.
McCain turned to Connecticut and Massachusetts, where many like-minded moderates reside. "It's great to be back here in this great state," he told Boston supporters from the steps of the Green Dragon Tavern.
Romney, who holds a presumed edge in his home state, shrugged off the McCain incursion. "If he wants to spend time in Massachusetts, that's fine," said Romney, who worked the suburbs of Chicago and St. Louis. "I don't think it will help him a lot."
Huckabee stuck to Georgia and Tennessee, where Southern kinship might work in his favor.
All three tried to maximize their reach with stints on national Sunday morning TV talk shows.
McCain told CBS that his record was "more conservative than Gov. Romney says." He went on to portray Romney as an opportunist who lacks core principles.
"I went to Iowa and told them that I was against subsidies for ethanol; he was for them," McCain said, alluding to a major issue in farm states that produce fuel from crops. "I went to Michigan and said the old automobile jobs aren't coming back -- new ones are, but old ones aren't. He wants to give . . . $20 billion to Detroit over four years."
Joining McCain in New England was his mother, Roberta, 95. "She's been a great, great asset, particularly whenever the age issue comes up," McCain, 71, half-joked to Fox News.
Responding to her recent remark that conservatives would be "holding their nose" to vote for him, McCain said, "I love my mother dearly, more than anything in the world, but really, my mom is not a complete expert on this issue."
McCain, who was heckled by war protesters at a rally in Fairfield, Conn., said he expected to unite the party's factions once he won the nomination. He plans to travel late this week to Germany for a security conference and might go to Iraq.
"If we win, and have the nomination sewn up," McCain said, knocking on a table at the back of his bus, "then you take a little time off."
Romney struck a more aggressive posture. He told CNN that McCain had "been around a long time," and he dismissed him as a "lifelong Washington politician" who was ill-suited to guide the country out of its economic troubles.
"It's interesting to see how Washington politicians think about action," said Romney, who has stressed his private-sector resume as an investment executive and leader of the 2002 Salt Lake City Winter Olympics. "For them, it's reaching across aisles, and committee meetings and bills. Action where I come from means getting the job done."
At a rally outside Chicago, Romney stood before a "Washington Is Broken" sign, but was introduced by former Rep. J. Dennis Hastert of Illinois, the longest-serving Republican speaker of the House.
At the risk of putting off moderates in the Northeast and California, Romney also slammed McCain for opposing oil drilling in the Arctic National Wildlife Refuge and pushing a bill to stem global warming that he said would boost gasoline prices.
Romney cast himself as a sterling conservative, citing support from radio personality Rush Limbaugh and others on the right. Conservatives, he told CNN, are saying: "Whoa, we have to get behind Mitt Romney" and "We really can't afford John McCain as the nominee of our party."